Objective To explore the clinical value of mini instruments in breast approach endoscopic thyroidectomy (BAET). Methods We retrospectively analyzed the data of 40 patients receiving BAET with mini instrument in our department of Changzheng Hospital from Sep. 2012 to Dec. 2013. The average age of patients was (33.53±8.76) years old and the tumor size was (21.10±10.96) mm. According to intraoperative frozen pathology, 19 cases underwent unilateral lobectomy, six cases underwent subtotal thyroidectomy, seven cases underwent total thyroidectomy, and eight cases underwent radical resection of thyroid carcinoma. Results Forty BAET procedures with mini instruments were completed successfully without conversion to open operation, and the complete tumor resection was achieved in all cases. The average operative time was (112.25±31.52) min in the patients, and the VAS-12 h, VAS-24 h, VAS-48 h and RSS (cosmetic score) were 2.48±1.13, 0.85±0.8, 0.25±0.44 and 8.75±1.26, respectively. Four patients had temporary hypocalcemia and one had recurrent laryngeal nerve paralysis after operation. Conclusion Application of mini instruments in BEAT can make endoscopic thyroidectomy less invasive and can improve the cosmetic results, without increasing the surgical difficulty and complications.